But I want to know how to add assignments to the different factions. For example my mass spectrum has a peak at 181 (100) and another at 166 (50). I know that the difference is 15 so this corresponds to CH3, but how do I report this in the RSC style?

(Please don't just paste an excerpt from a journal; I would much prefer an explanation)

I'm still confused on how to report assignments to mass spectroscopy. For example my mass spectrum has a peak at 181 (100) and another at 166 (50). I know that the difference is 15 so this corresponds to CH3. If someone could show me how to report this by including the CH3 assignment to the peak difference I would be extremely grateful!